The present invention relates to flow separating and concentrating devices and, more particularly, flow units and methods of separating and concentrating microfluidic particles.
Separation of cells, bacteria, or other particles is a process typically performed in biological, medical, and chemical research. Many technologies have been developed to replace conventional gradient methods that require bulky centrifuges and separation tubes. Many of such methods and apparatus are not practical for implementation in a miniaturized or microsized and automated system. For example, field-flow fractionation (FFF) involves a flexible elution technique of simultaneous separation and measurement. Such technique requires outer fields such as gravitational fields, electrical fields, thermal gradients, or cross flow fields.
Although other techniques may not require outer fields mentioned above, many of these techniques are not continuous and require a relatively long separation time and relatively complex injecting devices. For example, capillary hydrodynamic fraction (CHDF) is a technique that was used to analyze the size distribution of particle growth during emulsion polymerization. Moreover, hydrodynamic chromatography (HDC) is a technique that has been tested on separation of fluorescent nano-spheres and macromolecules. Although both CHDF and HDC do not require external fields, these separation processes are (as mentioned) not continuous and require a relatively long separation time and complicated injecting devices. These attributes are not suitable for large-scale cell or particle preparation.
Furthermore, a preparative scale separation technique, pinched inlet split-flow thin fractionation (SPLITT) may be applied for the continuous size sorting of airborne particles. However, it requires external fields (e.g., gravitation fields) as in the case with FFF.